<!doctype html>
<html lang="en">

<head>
  <title>GET VIDEO</title>
  <meta charset="utf-8">
  <!-- <script src="{{ url_for('static', filename='js/jquery-1.7.1.min.js') }}"></script> -->
  <script type="text/javascript" src="//cdn.bootcss.com/jquery/3.1.1/jquery.min.js"></script>
</head>

<body>
  <input type="button" title="开启摄像头" value="开启摄像头" onclick="getMedia()" />
  <video id="video" width="500px" height="500px" autoplay="autoplay"></video>
  <canvas id="canvas" width="500px" height="500px"></canvas>
  <button id="snap" onclick="takePhoto()">拍照</button>
  <button id="close" onclick="closeMedia()">关闭</button>
  <button id="upload" onclick="uploadImage()">上传</button>

  <script>

    function closeMedia() {
      var video = document.getElementById('video');
      if (!video.srcObject) return
      let stream = video.srcObject
      let tracks = stream.getTracks();
      tracks.forEach(track => {
        track.stop()
      })
    }
    //获得video摄像头区域
    let video = document.getElementById("video");
    function getMedia() {
      let constraints = {
        video: { width: 500, height: 500 },
        audio: true
      };
      /*
      这里介绍新的方法:H5新媒体接口 navigator.mediaDevices.getUserMedia()
      这个方法会提示用户是否允许媒体输入,(媒体输入主要包括相机,视频采集设备,屏幕共享服务,麦克风,A/D转换器等)
      返回的是一个Promise对象。
      如果用户同意使用权限,则会将 MediaStream对象作为resolve()的参数传给then()
      如果用户拒绝使用权限,或者请求的媒体资源不可用,则会将 PermissionDeniedError作为reject()的参数传给catch()
      */
      let promise = navigator.mediaDevices.getUserMedia(constraints);
      promise.then(function (MediaStream) {
        video.srcObject = MediaStream;
        video.play();
      }).catch(function (PermissionDeniedError) {
        console.log(PermissionDeniedError);
      })
    }
    function takePhoto() {
      //获得Canvas对象
      let canvas = document.getElementById("canvas");
      let ctx = canvas.getContext('2d');
      ctx.drawImage(video, 0, 0, 500, 500);
    }
    //图片上传到服务器
    //获取Canvas的编码
    // < !--var video = document.getElementById('video'); -->
    var canvas = document.getElementById('canvas');
    var context = canvas.getContext('2d');
    function uploadImage() {
      canvas.width = 300;
      canvas.height = 300;
      context.drawImage(video, 0, 0, 300, 300);
      var imgData = canvas.toDataURL("image/jpg");
      imgData = imgData.replace(/^data:image\/(png|jpg);base64,/, "")
      //上传到后台。
      var uploadAjax = $.ajax({
        type: "post",
        //后端需要调用的地址
        url: "/receiveImage/",
        data: JSON.stringify({ "imgData": imgData }),
        contentType: "json/application",
        //设置超时
        timeout: 10000,
        async: true,
        success: function (htmlVal) {
          //成功后回调
        },
        error: function (data) {
        },
        //调用执行后调用的函数
        complete: function (XMLHttpRequest, textStatus) {
          if (textStatus == 'timeout') {
            uploadAjax.abort(); //取消请求
            //超时提示：请求超时，请重试
            alert("请求超时，请重试")
            //请求超时返回首页
            closeCard();
          }
        }
      });
    }
  </script>
</body>

</html>